NEA Bubbler Condenser Project

There are 14 nuclear power plants of the VVER-440/213 type operating in the Czech Republic, Hungary, the Slovak Republic, Russian Federation and Ukraine. VVER-440/213 pressurised water reactors have a pressure suppression containment structure called a Bubbler Condenser (BC) tower which can reduce the design pressure of the entire confinement volume following a design-basis accident (DBA), such as a loss-of-coolant-accident (LOCA). The bubbler condenser pressure suppression system reduces the LOCA confinement pressure by expanding the released steam to a large volume and allowing it to condense in a water pool. The thermodynamic principle of the bubbler condenser function is identical to the function of the containments in western boiling water reactors with pressure suppression systems, but the boundary conditions (construction and dimensions) are different.

This project was set up to provide answers to remaining questions about the BC tower's performance under accident conditions by means of experiments carried out at the Electrogorsk Research Center (EREC) in the Russian Federation. Experts from the Czech Republic, France, Germany, Hungary, the Slovak Republic and the United States participated in the project; the European Union also took part. Czech, Hungarian and Slovak utilities provided the financing for the test programme.

Project meetings held in 2001 and 2002 addressed the current status of research on the subject, agreed on the experiments to be carried out under the project's auspices and oversaw the co-ordination of these experiments with other initiatives, notably those taken by the European Union. The three experiments that were agreed as a result of these project meetings have now been completed. The results have been analysed and an activity report for the project is now available. Based on these tests, the project's steering group has concluded that the related loads during DBAs do not represent a challenge to the bubbler condenser's confinement integrity.